The present disclosure relates to radar systems and methods. Radar is an object detection system that uses electromagnetic waves to identify range, altitude, direction, and/or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, terrain and people. Radar is sometimes referred to as radio detection and ranging. Conventional radar systems have a transmitter that emits radio waves. When transmitted radio waves contact an object the radio waves are scattered in all directions. A portion of the radio waves is thus reflected back towards the radar system. Reflected radio waves have a slight change of wavelength (and thus frequency) if the target is moving. Radar systems also include a receiver. The receiver is typically located in a same location as the transmitter. Although the reflected signal is usually very weak, the reflected signal can be amplified through use of electronic techniques in the receiver and in the antenna configuration. Such amplification enables a radar unit to detect objects at ranges where other emissions from a target object, such as sound or visible light, would be too weak to detect. Radar uses include meteorological detection of precipitation, measuring ocean surface waves, air traffic control, police detection of speeding traffic, and military applications.
The present disclosure also relates to networks. One type of network is known as a wireless ad hoc network. A wireless ad hoc network is a decentralized wireless network. The network is ad hoc because it does not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity. The decentralized nature of wireless ad hoc networks makes them suitable for a variety of applications where central nodes cannot be relied on, and may improve the scalability of wireless ad hoc networks compared to wireless managed networks. Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like natural disasters or military conflicts.
An ad-hoc network is made up of multiple “nodes” connected by “links”. Links are influenced by the node's resources (e.g. available energy supply, transmitter power, computing power and memory) and by behavioral properties (reliability, and trustworthiness), as well as by link properties (e.g. line-of-sight interference, length-of-link and signal loss, interference and noise). Since new and old links can be connected or disconnected at any time, a functioning network must be able to cope with this dynamic restructuring, preferably in a way that is timely, efficient, reliable, robust and scalable. The network must allow any two nodes to communicate, often via other nodes that relay the information. A “path” is a series of links that connects two nodes. Often there are multiple paths between any two nodes. Many of these applications use battery-powered nodes whose uninterrupted service life is limited by the energy efficiency of the node itself.